Technical Field
The present invention relates to an organoclay comprising Ditallow-dimethyl-ammonium salt and a phyllosilicate, an emulsified gel using the organoclay and a polyethyleneimine cross-linked polyacrylamide chain, and a method for using the emulsified gel.
Description of the Related Art
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.
Stavland et.al (2006) (Arne Stavland, Knut Inge Andersen, Bernt Sandoey, Tore Tjomsland, Amare Ambaye Mebratu: “How to apply a blocking gel system for bullhead selective water shutoff: From Laboratory to field”, SPE 2006) (incorporated herein by reference in its entirety) proposed a new mechanism for water control in oil fields liable to high water production during oil exploration. This new mechanism involved injecting water-based emulsified gelant into the formation. In their investigation, emulsion was designed such that it separated into a water phase and oil phase at static conditions in the formation. Following the reaction in the formation, it was expected that the water phase gels up while the oil phase remains mobile.
Cross-linked polymeric gels especially polyacrylamide gels are widely used in petroleum industries to minimize water production during oil and gas exploration and production. Aqueous polymer gels are usually emulsified in oil and then injected in the water zones. The purpose of the emulsification is to provide open pathways for oil flow. This is because in water wet media, the gel formed will block pore throats and reduce the permeability to water and oil. Therefore, oil should form the external phase of the emulsion. The emulsion should be injected as one component, and then it will separate into oil phase (for oil flow) and water phase. The water phase contains the gelant which will gel up in a portion of the pore space to reduce permeability to water. Surfactants are usually used to emulsify the aqueous gel solution in oil.
Gelled or cross-linked water soluble polymers are widely used in many petroleum industries to reduce water production from high permeability zones in wellbores and increase oil production. For instance, such gelled polymers can be utilized to change the permeability of underground formations. In several water shut-off applications, polymers and suitable crosslinking agents or systems are pumped in an aqueous solution into the underground formation. The polymers permeate into regions having the highest water permeability and gel therein.